1. Field of the Invention
The present invention relates to an image processing apparatus for preventing the forgery of bills, etc. in a recording system for processing an image in a host computer and printing the image on a recording device.
2. Related Background Art
Many systems for preventing the forgery of bills, valuable securities, etc. are designed as input/output device built-in systems such as copying units, etc. However, with an increasing number of personal computers, high-performance peripheral devices such as a scanner, a digital camera, a printer, etc. have been developed. As a result, with these high-performance peripheral devices, the personal computers can output an image at a quality level higher than an image output by the input/output device built-in copying units. Thus, in a personal computer environment, a forgery preventing system is required.
As a characteristic of a forgery preventing system in the personal computer environment, a host computer controls input and output devices. Therefore, it is necessary to allow an image process program of the host computer to recognize specified patterns of bills, valuable securities, etc. A personal computer can output data without a specific image process program only if it is informed of the control code of the output device.
Accordingly, a method of encrypting the control code of the output device is effective to prevent the use of a program other than the specific image process program for a forgery preventing process. The above mentioned method is disclosed by, for example, by Japanese Patent Application Laid-Open No. 6-105141 although not in the personal computer environment. FIG. 2 shows an example when this method is applied to the personal computer environment.
In FIG. 2, the processes in steps S2001 to S2005 are performed by the host computer, and the processes in steps S2006 to S2009 are performed by the recording device.
In the first step S2001, image data is input from an OS (basic software) or an application. Then, in step S2002, an image process including a forgery preventing process is performed. The image process in step S2002 includes color matching, gamma correction, and quantizing processes to convert an input image into print image data. In the forgery preventing process in step S2002, determination is normally made on a specified image by performing a pattern recognizing process. If the input image matches the specified image, then an error process is performed on the image data.
Then, the print data on which an image process has been performed is encrypted in step S2003. The encrypted print data is converted into print control data as a command for control of a printer in step S2004.
The print control data as a command is transferred to the printer by controlling (control can be practically performed by the OS) the data transfer circuit (not shown in the attached drawings) in step S2005.
Next, in step S2006, the printer receives the print control data. A command analyzing process is performed on the received print control data in step S2007, and encrypted print image data is generated.
Then, the encrypted print image data is converted into print data in a decryption process in step S2008, and the decrypted print data is printed on a storage medium in step S2009.
However, since in the above mentioned system which performs the encryption process between the host computer and the printer, there is an one to one correspondence between the input image and the data transferred to the printer, the encrypted data can be easily decrypted.
That is, it is the same as the case where the control code of the printer used in the conventional system is not open, and there is a problem that the image forgery preventing process cannot be effectively performed.